[python] replace api-version 2021-03-01 with 2021-05-01 (#16618)

* Update readme.python.md

* Update readme.python.md

* Update readme.python.md

Author: msyyc

specification/network/resource-manager/readme.python.md

@@ -17,7 +17,7 @@ Generate all API versions currently shipped for this package
 ```yaml $(multiapi)
 clear-output-folder: true
 batch:
-  - tag: package-2021-03
+  - tag: package-2021-05
   - tag: package-2021-02
   - tag: package-2021-02-preview-only
   - tag: package-2020-11
@@ -44,9 +44,7 @@ batch:
   - tag: package-2018-04
   - tag: package-2018-02
   - tag: package-2018-01
-  - tag: package-2017-11
   - tag: package-2017-10
-  - tag: package-2017-09
   - tag: package-2017-06
   - tag: package-2017-03
   - tag: package-2016-12
@@ -62,6 +60,16 @@ clear-output-folder: false
 perform-load: false
 ```
 
+### Tag: package-2021-05 and python
+
+These settings apply only when `--tag=package-2021-05 --python` is specified on the command line.
+Please also specify `--python-sdks-folder=<path to the root directory of your azure-sdk-for-python clone>`.
+
+``` yaml $(tag) == 'package-2021-05'
+namespace: azure.mgmt.network.v2021_05_01
+output-folder: $(python-sdks-folder)/network/azure-mgmt-network/azure/mgmt/network/v2021_05_01
+```
+
 ### Tag: package-2021-02-preview-only and python
 
 These settings apply only when `--tag=package-2021-02-preview-only --python` is specified on the command line.
@@ -72,15 +80,6 @@ namespace: azure.mgmt.network.v2021_02_01_preview
 output-folder: $(python-sdks-folder)/network/azure-mgmt-network/azure/mgmt/network/v2021_02_01_preview
 ```
 
-### Tag: package-2021-03 and python
-
-These settings apply only when `--tag=package-2021-03 --python` is specified on the command line.
-Please also specify `--python-sdks-folder=<path to the root directory of your azure-sdk-for-python clone>`.
-
-``` yaml $(tag) == 'package-2021-03'
-namespace: azure.mgmt.network.v2021_03_01
-output-folder: $(python-sdks-folder)/network/azure-mgmt-network/azure/mgmt/network/v2021_03_01
-```
 
 ### Tag: package-2021-02 and python
 
@@ -332,16 +331,6 @@ namespace: azure.mgmt.network.v2018_01_01
 output-folder: $(python-sdks-folder)/network/azure-mgmt-network/azure/mgmt/network/v2018_01_01
 ```
 
-### Tag: package-2017-11 and python
-
-These settings apply only when `--tag=package-2017-11 --python` is specified on the command line.
-Please also specify `--python-sdks-folder=<path to the root directory of your azure-sdk-for-python clone>`.
-
-``` yaml $(tag) == 'package-2017-11'
-namespace: azure.mgmt.network.v2017_11_01
-output-folder: $(python-sdks-folder)/network/azure-mgmt-network/azure/mgmt/network/v2017_11_01
-```
-
 ### Tag: package-2017-10 and python
 
 These settings apply only when `--tag=package-2017-10 --python` is specified on the command line.
@@ -352,17 +341,6 @@ namespace: azure.mgmt.network.v2017_10_01
 output-folder: $(python-sdks-folder)/network/azure-mgmt-network/azure/mgmt/network/v2017_10_01
 ```
 
-### Tag: package-2017-09 and python
-
-These settings apply only when `--tag=package-2017-09 --python` is specified on the command line.
-Please also specify `--python-sdks-folder=<path to the root directory of your azure-sdk-for-python clone>`.
-
-``` yaml $(tag) == 'package-2017-09'
-namespace: azure.mgmt.network.v2017_09_01
-output-folder: $(python-sdks-folder)/network/azure-mgmt-network/azure/mgmt/network/v2017_09_01
-```
-
-
 ### Tag: package-2017-06 and python
 
 These settings apply only when `--tag=package-2017-06 --python` is specified on the command line.